Humidifier reservoir

ABSTRACT

An apparatus for humidifying a flow of pressurised, breathable air includes varying a first pressure of the flow of breathable gas to vary a level of thermal engagement between the conductive portion of the reservoir and the heater plate, varying a height of the variable portion varies a level of thermal engagement between the conductive portion of the reservoir and the heater plate, use of a humidifier reservoir base component with a maximum water capacity substantially equal to the predetermined maximum volume of water of the humidifier reservoir or the use of intersecting inlet and outlet axes.

1 CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.17/322,947, filed May 18, 2021, which is a continuation of U.S.application Ser. No. 15/825,166, filed Nov. 29, 2017, now U.S. Pat. No.11,013,881, which is a continuation of U.S. application Ser. No.14/211,346, filed Mar. 14, 2014, now U.S. Pat. No. 9,861,778, whichclaims the benefit of Australian Provisional Application No. 2013900901,filed Mar. 15, 2013, each of which is incorporated herein by referencein its entirety.

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in the Patent and TrademarkOffice patent file or records, but otherwise reserves all copyrightrights whatsoever.

2 BACKGROUND OF THE INVENTION 2.1 (1) Field of the Invention

[2] The present technology relates to one or more of the diagnosis,treatment and amelioration of respiratory disorders, and to proceduresto prevent respiratory disorders. In particular, the present technologyrelates to medical devices, and their use for treating respiratorydisorders and for preventing respiratory disorders.

2.2 (2) Description of the Related Art

The respiratory system of the body facilitates gas exchange. The noseand mouth form the entrance to the airways of a patient.

The airways consist of a series of branching tubes, which becomenarrower, shorter and more numerous as they penetrate deeper into thelung. The prime function of the lung is gas exchange, allowing oxygen tomove from the air into the venous blood and carbon dioxide to move out.The trachea divides into right and left main bronchi, which furtherdivide eventually into terminal bronchioles. The bronchi make up theconducting airways, and do not take part in gas exchange. Furtherdivisions of the airways lead to the respiratory bronchioles, andeventually to the alveoli. The alveolated region of the lung is wherethe gas exchange takes place, and is referred to as the respiratoryzone. See West, Respiratory Physiology—the essentials.

A range of respiratory disorders exist.

Obstructive Sleep Apnoea (OSA), a form of Sleep Disordered Breathing(SDB), is characterized by occlusion of the upper air passage duringsleep. It results from a combination of an abnormally small upper airwayand the normal loss of muscle tone in the region of the tongue, softpalate and posterior oropharyngeal wall during sleep. The conditioncauses the affected patient to stop breathing for periods typically of30 to 120 seconds duration, sometimes 200 to 300 times per night. Itoften causes excessive daytime somnolence, and it may causecardiovascular disease and brain damage. The syndrome is a commondisorder, particularly in middle aged overweight males, although aperson affected may have no awareness of the problem. See U.S. Pat. No.4,944,310 (Sullivan).

Cheyne-Stokes Respiration (CSR) is a disorder of a patient's respiratorycontroller in which there are rhythmic alternating periods of waxing andwaning ventilation, causing repetitive de-oxygenation and re-oxygenationof the arterial blood. It is possible that CSR is harmful because of therepetitive hypoxia. In some patients CSR is associated with repetitivearousal from sleep, which causes severe sleep disruption, increasedsympathetic activity, and increased afterload. See U.S. Pat. No.6,532,959 (Berthon-Jones).

Obesity Hyperventilation Syndrome (OHS) is defined as the combination ofsevere obesity and awake chronic hypercapnia, in the absence of otherknown causes for hypoventilation. Symptoms include dyspnea, morningheadache and excessive daytime sleepiness.

Chronic Obstructive Pulmonary Disease (COPD) encompasses any of a groupof lower airway diseases that have certain characteristics in common.These include increased resistance to air movement, extended expiratoryphase of respiration, and loss of the normal elasticity of the lung.Examples of COPD are emphysema and chronic bronchitis. COPD is caused bychronic tobacco smoking (primary risk factor), occupational exposures,air pollution and genetic factors. Symptoms include: dyspnoea onexertion, chronic cough and sputum production.

Neuromuscular Disease (NMD) is a broad term that encompasses manydiseases and ailments that impair the functioning of the muscles eitherdirectly via intrinsic muscle pathology, or indirectly via nervepathology. Some NMD patients are characterised by progressive muscularimpairment leading to loss of ambulation, being wheelchair-bound,swallowing difficulties, respiratory muscle weakness and, eventually,death from respiratory failure. Neuromuscular disorders can be dividedinto rapidly progressive and slowly progressive: (i) Rapidly progressivedisorders: Characterised by muscle impairment that worsens over monthsand results in death within a few years (e.g. Amyotrophic lateralsclerosis (ALS) and Duchenne muscular dystrophy (DMD) in teenagers);(ii) Variable or slowly progressive disorders: Characterised by muscleimpairment that worsens over years and only mildly reduces lifeexpectancy (e.g. Limb girdle, Facioscapulohumeral and Myotonic musculardystrophy). Symptoms of respiratory failure in NMD include: increasinggeneralised weakness, dysphagia, dyspnoea on exertion and at rest,fatigue, sleepiness, morning headache, and difficulties withconcentration and mood changes.

Chest wall disorders are a group of thoracic deformities that result ininefficient coupling between the respiratory muscles and the thoraciccage. The disorders are usually characterised by a restrictive defectand share the potential of long term hypercapnic respiratory failure.Scoliosis and/or kyphoscoliosis may cause severe respiratory failure.Symptoms of respiratory failure include: dyspnoea on exertion,peripheral oedema, orthopnoea, repeated chest infections, morningheadaches, fatigue, poor sleep quality and loss of appetite.

Otherwise healthy individuals may take advantage of systems and devicesto prevent respiratory disorders from arising.

2.2.1 Systems

One known product used for treating sleep disordered breathing is the S9Sleep Therapy System, manufactured by ResMed.

2.2.2 Therapy

Nasal Continuous Positive Airway Pressure (CPAP) therapy has been usedto treat Obstructive Sleep Apnea (OSA). The hypothesis is thatcontinuous positive airway pressure acts as a pneumatic splint and mayprevent upper airway occlusion by pushing the soft palate and tongueforward and away from the posterior oropharyngeal wall.

Non-invasive ventilation (NIV) has been used to treat OHS, COPD, MD andChest Wall disorders.

2.2.3 Patient Interface

The application of a supply of air at positive pressure to the entranceof the airways of a patient is facilitated by the use of a patientinterface, such as a nasal mask, full-face mask or nasal pillows. Arange of patient interface devices are known, however a number of themsuffer from being one or more of obtrusive, aesthetically undesirable,poorly fitting, difficult to use and uncomfortable especially when wornfor long periods of time or when a patient is unfamiliar with a system.Masks designed solely for aviators, as part of personal protectionequipment or for the administration of anaesthetics may be tolerable fortheir original application, but nevertheless be undesirablyuncomfortable to be worn for extended periods, for example, whilesleeping.

2.2.4 PAP Device

PAP devices are used to deliver positive airway pressure in many forms.For example, a positive pressure level may be maintained across theinspiratory and expiratory levels of the patient's breathing cycle at anapproximately constant level. Alternatively, pressure levels may beadjusted to change synchronously with the patient's breathing cycle. Forexample, pressure may be set at one level during inspiration and anotherlower level during expiration for patient comfort. Such a pressuretreatment system may be referred to as bi-level. Alternatively, thepressure levels may be continuously adjusted to smoothly replicatechanges in the patient's breathing cycle. A lower pressure settingduring expiration may generally be referred to as expiratory pressurerelief.

In providing such changes to pressure and/or detecting conditions formaking adjustments to the treatment pressure, it can be helpful to havea measure or estimation of patient respiratory flow or total volumetricflow. For example, a flow signal may be utilized to detect when apatient changes from inspiration to expiration for determining when todeliver expiratory pressure treatment settings or inspiratory pressuretreatment settings. Similarly, the flow signal may be utilized to detectpatient flow limitation for purposes of making treatment pressureadjustments. Such adjustments are illustrated in the U.S. Pat. No.5,704,345. For these purposes, a measured flow signal may be derivedfrom a flow sensor such as a differential pressure transducer orpnuemotachograph. Alternatively, the flow signal may be estimated in theabsence of a flow sensor.

2.2.5 Humidifier

Respiratory apparatuses commonly have the ability to alter the humidityof the breathable gas in order to reduce drying of the patient's airwayand consequent patient discomfort and associated complications. The useof a humidifier placed between the flow generator and the patientinterface produces humidified gas that minimizes drying of the nasalmucosa and increases patient airway comfort. In addition in coolerclimates, warm air applied generally to the face area in and about thepatient interface is more comfortable than cold air.

Many humidifier types are available, although the most convenient formis one that is either integrated with or configured to be coupled to therelevant respiratory apparatus. While passive humidifiers can providesome relief, generally a heated humidifier is required to providesufficient humidity and temperature to the air so that the patient willbe comfortable. Humidifiers typically comprise a water reservoir or tubhaving a capacity of several hundred milliliters (ml), a heating elementfor heating the water in the reservoir, a control to enable the level ofhumidification to be varied, a gas inlet to receive gas from the flowgenerator, and a gas outlet adapted to be connected to a patient conduitthat delivers the humidified gas to the patient's mask.

Typically, the heating element is incorporated in a heater plate whichsits under, and is in thermal contact with, the water tub. Thus, heat istransferred from the heater plate to the water reservoir primarily byconduction.

In the prior art, additional components have been used to improvethermal contact between the water reservoir and the heater plate. Oneexample is the use of spring elements, which are used to connect theheater plate to the humidifier body, as described in U.S. Pat. No.4,203,027, thereby pushing the heater plate towards the water reservoir.Another example is a humidifier with a lid wherein a compressibleelastomer seal is provided on the lid, as described in WO2010/031126. Inthis example, when the lid is in its closed position the seal engagesagainst the water reservoir and pushes it against the heater plate.

Another aspect of a prior art humidifier water reservoir is thatover-filling and/or tilting of the water reservoir may result in theflow of water back into the PAP device. The introduction of elongatedinlets such as those disclosed in WO 2004/026382 has reduced the risk ofspillage due to tilt, however the water reservoir still can beover-filled, and when this occurs it may reduce the effectiveness ofsuch spill-protection system. As a result, such prior art humidifierwater reservoirs have included a water filling indication mark to reduceoccurrence of such over-filling.

3 BRIEF SUMMARY OF THE INVENTION

The present technology is directed towards providing medical devicesused in the diagnosis, amelioration, treatment, or prevention ofrespiratory disorders having one or more of improved comfort, cost,efficacy, ease of use and manufacturability.

A first aspect of the present technology relates to apparatus used inthe diagnosis, amelioration, treatment or prevention of a respiratorydisorder.

Another aspect of the present technology relates to methods used in thediagnosis, amelioration, treatment or prevention of a respiratorydisorder.

One form of the present technology comprises a humidifier reservoir ortub comprising an internal variable portion, which generates a forcepushing the humidifier reservoir towards the heater plate when thehumidifier reservoir is engaged with the humidifier. The variableportion may also include a seal.

Another aspect of one form of the present technology is a humidifierreservoir comprising a variable element which is compressed andgenerates a force pushing the humidifier reservoir towards the heaterplate when the humidifier reservoir is engaged with the humidifier.

One form of the present technology comprises a humidifier reservoirwherein when the humidifier reservoir is engaged with the humidifier,the introduction of therapy pressure improves thermal engagement of thehumidifier reservoir with the heater plate.

Another aspect of one form of the present technology is a humidifierreservoir comprising a means of using therapy pressure that isintroduced within the humidifier reservoir to generate a force betweenthe humidifier reservoir and the heater plate to improve thermalcoupling between the humidifier reservoir and the heater plate.

One form of the present technology comprises a humidifier reservoircomprising an over-filling protection element configured to indicateover-filling.

In one form of the present technology the over-filling protectionelement may include at least one orifice in a wall of the reservoir. Theat least one orifice defines an egress path of water when thepredetermined maximum volume of water is exceeded.

In another form of the present technology the over-filling protectionelement may include a sloped profile in the side profile of a wall ofthe reservoir that defines an egress path of water when thepredetermined maximum volume of water is exceeded.

Another aspect of one form of the present technology is a humidifierreservoir comprising an over-filling protection element to prevent thehumidifier reservoir from filling beyond a predetermined or maximumcapacity.

One form of the present technology comprises a humidifier reservoircomprising an inlet and outlet arranged to prevent spillage of waterfrom the reservoir back through the inlet and/or outlet.

Of course, portions of the aspects may form sub-aspects of the presentinvention. Also, various ones of the sub-aspects and/or aspects may becombined in various manners and also constitute additional aspects orsub-aspects of the present invention.

Other features of the technology will be apparent from consideration ofthe information contained in the following detailed description,abstract, drawings and claims.

4 BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The present technology is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings, in whichlike reference numerals refer to similar elements including:

4.1 Treatment Systems

FIG. 1a shows a system in accordance with the present technology. Apatient 1000 wearing a patient interface 3000, receives a supply of airat positive pressure from a positive airway pressure (PAP) device 4000.Air from the PAP device is humidified in a humidifier 5000, and passesalong an air circuit 4170 to the patient 1000.

FIG. 1b shows a PAP device in use on a patient with a nasal mask.

FIG. 1c shows a PAP device in use on a patient with a full-face mask.

4.2 Therapy

4.2.1 Respiratory System

FIG. 2a shows an overview of a human respiratory system including thenasal and oral cavities, the larynx, vocal folds, oesophagus, trachea,bronchus, lung, alveolar sacs, heart and diaphragm.

FIG. 2b shows a view of a human upper airway including the nasal cavity,nasal bone, lateral nasal cartilage, greater alar cartilage, nostril,lip superior, lip inferior, larynx, hard palate, soft palate,oropharynx, tongue, epiglottis, vocal folds, oesophagus and trachea.

4.3 Patient Interface

FIG. 3a shows a patient interface in accordance with one form of thepresent technology.

4.4 PAP Device

FIG. 4a shows a PAP device in accordance with one form of the presenttechnology.

FIG. 4b shows a schematic diagram of the pneumatic components of a PAPdevice in accordance with one form of the present technology. Thedirections of upstream and downstream are indicated.

It should be understood that a number of components, such assupplementary O₂ 4180, anti-spill back valve 4160, or the transducer(s)4270 are optional. Also, in an alternative arrangement the humidifier5000 may be placed in alternative locations for example, upstream of thepneumatic block 4020.

4.5 Humidifier

FIG. 5a shows a simplified representation of a humidifier connected to ablower and a patient conduit

FIG. 5b shows a schematic of a humidifier.

4.6 Breathing Waveforms

FIG. 6a shows a model typical breath waveform of a person whilesleeping, the horizontal axis is time, and the vertical axis is flow.While the parameter values may vary, a typical breath may have thefollowing approximate values: tidal volume, Vt, 0.5 L, inhalation time,Ti, 1.6 s, peak inspiratory flow, Qpeak, 0.4 L/s, exhalation time, Te,2.4 s, peak expiratory flow, Qpeak, −0.5 L/s. The total duration of thebreath, Ttot, is about 4 s. The person typically breathes at a rate ofabout 15 breaths per minute (BPM), with Ventilation, Vent, about 7.5L/s. A typical duty cycle, the ratio of Ti to Ttot is about 40%.

4.7 PAP Device with a Humidifier

FIG. 7 shows a prior art example of a PAP device 4000 and a humidifier5000.

FIG. 8 shows an example of the present technology, showing a PAP device4000 and an integrated humidifier 5000.

FIGS. 9-12 show various views of a humidifier reservoir 5110 inaccordance with one aspect of present technology, wherein FIG. 9-10 showthe humidifier reservoir 5110 in a ‘closed’ configuration, FIG. 11 showsthe humidifier reservoir 5110 in an ‘open’ configuration, and FIG. 12 isan exploded view of the humidifier reservoir 5110.

FIGS. 13-16 show the humidifier 5000 from various perspectives, inparticular demonstrating the engagement of the humidifier reservoir 5110with the reservoir dock 5130.

FIGS. 17-19 show a time-lapse chart of an exemplary flow path of gas asit enters the humidifier reservoir 5110 through the inlet 5118 and exitsthrough the outlet 5122 after traversing through the inside of thehumidifier reservoir 5110.

FIGS. 20-21 show exemplary distributions of pressure/force in thehumidifier reservoir 5110 in various configurations.

FIGS. 22-29 show varying configurations of the reservoir lid 5114, inparticular variations in configurations of the inlet tube 5124 and theoutlet tube 5126 according to aspects of the present technology.

FIGS. 30a and 30b show the humidifier reservoir 5110 and in particularthey aim to show the orifice 5138 according to an example of the presenttechnology.

FIGS. 30c and 30d show the humidifier base 5112 and in particular thesloped profile 5139 according to an example of the present technology.

FIG. 31 shows the humidifier reservoir 5110 and in particular theorifice 5138 according to an example of the present technology.

FIGS. 32-33 show the humidifier dock 5130 and the humidifier reservoir5110, and in particular show the interaction between the lid protrusion5142 and the dock locking recess 5144 according to one aspect of thepresent technology.

FIG. 34 show an example of the humidifier reservoir 5110 according toanother example of the current technology, wherein it is configured witha re-filling cap 5180 and a base, top and variable portion may beaffixed together.

FIGS. 35-38 shows other representations of a humidifier reservoir 5110according to an aspect of the present technology, with particular regardto the arrangement of the inlet tube 5124 and the outlet tube 5126.

FIG. 39 shows a cross-sectional view of a reservoir lid 5114 and avariable portion in the form of a seal 5116 according to an aspect ofthe present technology.

FIG. 40 shows an example of the humidifier reservoir 5110 according toanother example of the present technology, wherein it is configured witha latch 5186.

5 DETAILED DESCRIPTION OF THE INVENTION

Before the present technology is described in further detail, it is tobe understood that the technology is not limited to the particularexamples described herein, which may vary. It is also to be understoodthat the terminology used in this disclosure is for the purpose ofdescribing only the particular examples discussed herein, and is notintended to be limiting.

5.1 Treatment Systems

In one form, the present technology comprises apparatus for treating arespiratory disorder. Preferably the apparatus comprises a flowgenerator or blower for supplying pressurised respiratory gas, such asair, to the patient 1000 via an air delivery tube leading to a patientinterface 3000.

5.2 Therapy

In one form, the present technology comprises a method for treating arespiratory disorder comprising the step of applying positive pressureto the entrance of the airways of a patient 1000.

5.2.1 Nasal CPAP for OSA

In one form, the present technology comprises a method of treatingObstructive Sleep Apnea in a patient by applying nasal continuouspositive airway pressure to the patient.

5.3 Patient Interface 3000

A non-invasive patient interface 3000 in accordance with one aspect ofthe present technology comprises the following functional aspects aseal-forming structure 3100, a plenum chamber 3200, a positioning andstabilising structure 3300 and a connection port 3600 for connection toan air circuit 4170. In some forms a functional aspect may be providedby one or more physical components. In some forms, one physicalcomponent may provide one or more functional aspects. In use theseal-forming structure 3100 is arranged to surround an entrance to theairways of the patient so as to facilitate the supply of air at positivepressure to the airways.

5.4 PAP Device 4000

A preferred PAP device 4000 in accordance with one aspect of the presenttechnology comprises mechanical and pneumatic components 4100,electrical components 4200 and is programmed to execute one or morealgorithms 4300. FIG. 7 shows a prior art embodiment of a PAP device4000, which is connectable to a humidifier 5000. The PAP device may alsobe integrated with a humidifier 5000 so that an external housing 4010encases the components that perform the equivalent function of a PAPdevice 4000 as well as components that perform the equivalent functionof a humidifier 5000.

FIG. 8 shows an example embodiment of such an integrated devicecomprising a PAP device 4000 and a humidifier 5000. It should beunderstood that subsequent references to a humidifier 5000 refers to theintegrated device, in particular the components that perform theequivalent function of a humidifier 5000.

5.5 Humidifier 5000

5.5.1 Humidifier Overview

In one form of the present technology there is provided a humidifier5000 comprising a water reservoir 5110, a heater plate 5120 and a waterreservoir dock 5130.

5.5.2 Humidifier Mechanical Components 5100

5.5.2.1 Water Reservoir Dock 5130

A water reservoir dock 5130 may be integrated with the humidifier 5000as shown in FIG. 13-16. In this arrangement, the reservoir dock 5130comprises a breathable gas outlet 5168 to output a flow of breathablegases to a water reservoir 5110, a humidified breathable gas inlet 5170to receive the flow of breathable gases that has been humidified in thewater reservoir 5110, and an air delivery conduit outlet 5172 totransfer the flow of humidified breathable gases to the air deliveryconduit 4170. As shown in FIG. 14, the water reservoir dock 5130 mayform a cavity 5160 to receive the water reservoir 5110. The cavity 5160may include a top portion configured to cover at least a portion of thelid of the reservoir 5110 and a bottom portion including the heaterplate 5020.

It should be understood that the reservoir dock 5130 may be providedseparately to a humidifier 5000 in an alternate arrangement. In such anarrangement, additional interfaces may be used to connect the reservoirdock 5130 to the humidifier 5000.

In another arrangement, a water reservoir dock 5130 may comprise anopening in a substantially horizontal plane, so that the water reservoir5110 may be inserted from above or below the water reservoir dock 5130.

5.5.2.2 Water Reservoir 5110

FIG. 9-12 show an example of a water reservoir 5110 according to thetechnology, which comprises a reservoir base 5112, a reservoir lid 5114,and a variable portion 5116. As shown in this example arrangement thevariable portion 5116 may also function as a seal between the base 5112and the reservoir lid 5114. The reservoir forms a cavity formed by aplurality of walls to hold a volume of liquid or water. The cavity ofthe reservoir 5110 is configured so that it is able to hold a given,maximum volume of liquid or water, typically several hundredmillilitres, for example 300 millilitres (ml), 325 ml, 350 ml or 400 ml,although it is to be understood that other volumes of liquid may beutilised such as 100 ml, 200 ml, 250 ml, 500 ml or more or less.

The lid 5114 may comprise an inlet 5118 and an outlet 5122. The inlet5118 comprises an inlet tube 5124 and the outlet 5122 comprises anoutlet tube 5126. The lid 5114 may be pivotably connected to the base5112 by hinges 5158 in such a way that it is able to be moved between anopen position, as shown in FIG. 11, and a closed position, as shown inFIG. 9 and FIG. 10. When the water reservoir 5110 is in its closedconfiguration, the variable portion 5116 is put into sealing engagementbetween the base 5112 and the lid 5114.

The variable portion 5116 may be provided as part of the reservoir lid5114 or as part of the reservoir base 5112, or independently of both.The variable portion 5116 may be engaged with the reservoir lid 5114 orthe reservoir base 5112 by any number of means including, and notlimited to, ultrasonic welding, friction fitting, gluing or by using anintermediate component. The variable portion 5116 may comprise a carrier5117 (as shown in FIG. 12).

In an arrangement, the variable portion 5116 may not be directly engagedwith the base 5112 or lid 5114 but coupled to one or both of the lid5114 and the base 5112 such that each of the base 5112 and the lid 5114may be formed as two separate parts that are able to be assembled withthe variable portion 5116 coupled therebetween. Alternatively thevariable portion 5116 may be coupled to either the lid 5114 or the base5112.

In an alternative arrangement the variable portion 5116 may be locatedwithin a wall of the reservoir base 5112 and/or a wall of the reservoirlid 5114 rather than being on the edge of either the reservoir base 5112or the reservoir lid 5114. Thus, in such an arrangement the variableportion would not be between the reservoir base 5112 and the reservoirlid 5114 but within the reservoir base 5112 and/or the reservoir lid5114. There may be more than one variable portion 5116 to provide morecompliance in movement of the reservoir 5110.

The reservoir base 5112 comprises a conducting portion that isconfigured to couple with a heater plate 5130 of the humidifier to allowthermal engagement and thermal transfer of heat to the liquid or waterwithin the base. The base may comprise a base upper body 5146, a basebottom plate 5148, and a conducting portion in the form of a baseconductor plate 5152, as shown in FIG. 12. All or a part of the baseconductor plate 5152 may be made of a different material (e.g. aluminiumor another heat conducting metal) than the base upper body 5146 and/orthe base bottom plate 5148, which may be made of a plastic orthermoplastic polymer, for example, a polycarbonate material. The baseconductor plate 5152 may comprise of a sealing element 5150, which maybe integrated to, and/or sealingly connected to both the base upper body5146 and the base bottom plate 5148 to prevent egress of water from thewater reservoir 5110 through its bottom.

It should be appreciated that the reservoir base 5112 may be constructedin any number of parts. The reservoir base 5112 may be constructed as asingle part made of, for example, aluminium or another heat conductingmetal. In another arrangement, the reservoir base 5112 may beconstructed in multiple parts such as two parts comprising a lowercomponent and an upper component. The lower component may include: areservoir base conductor plate 5152, sealing element 5150 and basebottom plate 5148. The base bottom plate is constructed at least in partfrom a heat conducting material, for example, aluminium or another heatconducting metal. The upper component may include a base upper body 5146constructed from, for example, a polycarbonate material. The upper andlower components may be sub-divided to form further arrangementsconsisting of greater number of parts, for example the sealing element5150 may be a separate component.

Water Reservoir-to-Humidifier Connection

When in use, the water reservoir 5110 is removably coupled with thehumidifier 5000 as shown in FIG. 13-16 by inserting the water reservoirinto the water reservoir dock 5130, for example by sliding, so that theinlet 5118 of the water reservoir 5110 is configured to receive the flowof breathable air that is output by the PAP device 4000, and to directthe flow of breathable air into the water reservoir 5110. Moisture isadded to the flow of breathable air as the breathable air travelsthrough the reservoir 5110, and the humidified flow of breathable airexits the reservoir 5110 through the outlet tube 5126 and to thereservoir outlet 5122. The reservoir outlet 5122 is connectable to anair delivery circuit or air delivery conduit 4170 to deliver the flow ofhumidified breathable air to the patient 1000.

The double-ended arrows in FIG. 14 and FIG. 16 show the direction ofrelative motion, i.e. generally horizontal movement, between thehumidifier 5000 and the water reservoir 5110 in connecting anddisconnection with each other in this arrangement. However, it is notedthat the water reservoir 5110 may be coupled to the humidifier 5000 byother means such as being inserted into the humidifier in a generallyvertical direction. In the illustrated arrangement the reservoir outlet5122 is connected to the reservoir dock outlet 5168, through which thehumidified flow of breathable air travels to the humidifier outlet 5172.The humidifier outlet 5172 is connectable to the air delivery circuit orair delivery conduit 4170 as indicated in FIG. 13 by the double-endedarrow. One feature of such an arrangement is that the humidifierreservoir 5110 must be removed from the reservoir dock 5130 to fill thehumidifier reservoir 5110 with water. This arrangement may reduce thelikelihood of the user over-filling the water reservoir 5110 over thegiven, maximum volume of liquid or water, as the humidifier reservoir5110 incorporates means to prevent over-filling when the lid 5114 is inits open position as described further below.

As shown in FIG. 16, first and second dock seals 5132, 5134 may beprovided to seal the connection between the reservoir inlet 5118 and thedock 5130 and the connection between the reservoir outlet 5122 and thedock 5130.

Reservoir Handles

FIG. 13-16 show an upper handle 5154 that is located on the reservoirlid 5114, and a lower handle 5156 that is located on the reservoir base5112. These handles are intended to assist the patient 1000 to grip andhold the water reservoir 5110. In the shown arrangement, the handles5154 5156 are located away from the hinges 5158 such that by holding thereservoir 5110 by the handles 5154 5156 the patient 1000 imparts forcesonto the reservoir 5110 compressing the variable portion 5116, whichpushes the lid 5114 and the base 5112 towards each other. Thiscompression force may also help maintain the variable portion 5116 insealing engagement between the reservoir base 5112 and the reservoir lid5114. It is to be understood that the handles 5154 and 5156 may beplaced on other components or areas of the water reservoir 5110. Afriction grip 5166 may be provided on a surface of either or both of thehandles 5154 5156 as shown in FIG. 14. The friction grip 5166 may beconstructed from a higher friction material than the primary materialused to construct the water reservoir 5110. For example, the frictiongrip 5166 may be constructed from an elastomeric material such assilicone whereas the water reservoir 5110 may primarily be constructedfrom a polycarbonate material.

Reservoir Variable Portion

In the illustrated arrangement, when the water reservoir 5110 is in use,the variable portion 5116 is maintained in sealing engagement betweenthe reservoir base 5112 and the reservoir lid 5114. However, asmentioned above the variable portion 5116 may alternatively be formed aspart of the reservoir base 5112 and/or the reservoir lid 5114 and notform a seal between the reservoir base 5112 and the reservoir lid 5114.The variable portion 5116 may be constructed from an elastomericmaterial such as silicone, TPE, TPE polyester, TPE polyurethane ornatural rubber. In choosing the material to be used for the variableportion 5116 it may be advantageous to choose one that does notexperience mechanical relaxation across the range of storage andoperational temperatures that the variable portion 5116 may be exposedto. One example of a material for the variable portion 5116 which meetsthese requirements may be silicone.

In the arrangement shown in FIG. 15-16, the water reservoir 5110 isconnected with the humidifier 5000 by placing the water reservoir 5110in the water reservoir dock 5130. In this arrangement, the heights andshapes of the dock internal cavity 5160 and the water reservoir 5110 aresuch that when the water reservoir 5110 is engaged with the waterreservoir dock 5130 the variable portion 5116 is compressed, for exampleby between about 1 mm and about 5 mm, for example by about 2 mm, about 3mm or about 4 mm. Thus, the shape of the portion of the water reservoir5110 that is inserted into the dock 5130 is complementary to the shapeof the dock cavity 5160 and the height of the water reservoir 5110 whenvariable portion 5116 is compressed is slightly less than the height ofthe dock cavity 5160 to enable the insertion of the water reservoir 5110into the dock cavity 5160. The variable portion 5116 may be constructedwith a cross-section shape such as one shown in FIG. 39. A compressiveforce is required to sufficiently compress the variable portion to allowrelative movement, such as sliding between the water reservoir 5110 andthe water reservoir dock 5130. For example a compression force asmeasured at the handle recesses 5154, 5156 of between about 10 N andabout 30 N, or about 20 N, or some other compression force as requiredto allow insertion of the water reservoir 5110 into the dock cavity5160. The vertical gap achieved between the water reservoir 5110 and thedock internal cavity 5160 may be between about 1 mm and about 5 mm, forexample about 2 mm, 3 mm or 4 mm, when the compressive force is appliedat the handle recesses and the water reservoir 5110 is connected withthe reservoir dock 5130. The water reservoir 5110 and the reservoir dock5130 may be arranged so that the amount of compression in the variableportion 5116 is reduced once the water reservoir 5110 is connected withthe reservoir dock 5130 and the patient 1000 is no longer applying acompressive force. The reduction in compression may be between about 0.5mm and about 2.5 mm, for example about 1 mm, 1.5 mm or 2 mm.

A reservoir latch 5186 may be provided on the water reservoir 5110, asshown in FIG. 39, so that when the reservoir latch 5186 is engaged, itsecures the reservoir lid 5114 and reservoir base 5112 together toprevent the reservoir lid 5114 and the reservoir base 5112 fromseparating and maintains the variable portion 5116 in a compressedstate. The latch may also maintain the variable portion 5116 in sealingengagement between the lid 5114 and the base 5112 when the variableportion 5116 is located between the lid 5114 and the base 5112. Thelatch 5186 may be configured to allow further compression of thevariable portion 5116. This would allow insertion of the water reservoir5110 into the reservoir dock 5130 in the manner described above, and forthe variable portion 5116 to retain its advantageous propertiesregarding improvements to thermal engagement as described below.

In an alternative arrangement, not shown, the water reservoir 5110, maybe inserted into the dock cavity 5160 from a vertical direction ratherthan using a sliding motion. In such an arrangement the dock cavity ofthe humidifier 5000 may comprise a moveable cover portion, such as a lidor top portion, that is at least partially opened to allow insertion ofthe water reservoir 5110 and closed following insertion to secure thewater reservoir 5110 within the dock cavity 5160.

Air Flow Path

FIG. 17-19 show an exemplary path of the flow of breathable air throughthe reservoir 5110 as it enters through the inlet 5118 and exits throughthe outlet 5122. The figures are arranged chronologically in threedistinct orthogonal views per figure to demonstrate the exemplary flowpath visually. In this arrangement the flow of breathable air receivedthrough the inlet 5118 passes through the inlet tube 5124 (FIG. 17),into the internal volume of the water reservoir 5110 (FIG. 18), and thenpasses through the outlet tube 5126 to exit the water reservoir 5110 atthe outlet 5122 (FIG. 19) as humidified breathable air. FIG. 17-19 showthe reservoir 5110 with the lid 5114 and the base 5112 in exploded vieworientation for clarity, and any flow of the air that occurs in theinternal volume of the reservoir 5110 is shown in dotted lines, and thedirection of the arrows shown indicate the general direction of theexemplary flow of breathable air. Although it is noted that the natureof gas or air flow may involve the swirling of air rather than astraight and direct air flow path.

The path of the flow of breathable air demonstrated in FIG. 17-19 isexemplary only, and is aimed to demonstrate one of many paths that theflow of breathable air may traverse through, namely that it enters thewater reservoir 5110 through the inlet 5118 and exits through the outlet5122 after experiencing some degree of swirling within the volume of thewater reservoir 5110. A person skilled in the art would understand thatthe particles or molecules that form the flow of breathable air may notfollow a single path within the water reservoir 5110 due to a number offactors, including, for example, localised turbulence (eddies) orpressure gradients within the water reservoir 5110. As a result thecumulative path of the flow of breathable air may comprise any number ofpaths wherein it experiences various degrees of ‘swirling’ within thewater reservoir 5110 prior to exiting via the outlet tube 5126 at theoutlet 5122. It is also possible that some small portion of the flow ofbreathable air may escape the water reservoir 5110 as a leak.

Thermal Contact/Engagement

One aspect of this technology is improved thermal contact or engagementbetween the base 5112 of the water reservoir and the heater plate 5120of the humidifier. The improved thermal contact or engagement may befacilitated by the supply of pressurized gas to the humidifier reservoir5110 from a PAP device.

In one arrangement, the water reservoir 5110 may be configured so thatwhen it is placed in the water reservoir dock 5130 the reaction to thecompression of the variable portion 5116, i.e. a force attempting toexpand the variable portion 5116, pushes the base 5112 of the waterreservoir 5110 against the heater plate 5120 to improve the level ofthermal engagement between the heater plate 5120 and the base 5112. Thisoccurs as a result of the variable portion 5116 initially beingcompressed when it is inserted into the reservoir dock 5130 as describedabove, and then the compression is released or reduced allowing thevariable portion 5116 to expand towards its relaxed or uncompressedstate. Thus, the variable portion 5116 is acting like a spring that maybe biased to push the reservoir base 5112 and/or the reservoir lid 5114in a direction perpendicular to the heater plate 5120 until the variableportion 5116 is in a reduced compressed state. As the reservoir 5110 isconfined within the reservoir dock 5130 or by some other means the levelof compression of the variable portion 5116 is transferred as a forcethat encourages improved thermal engagement with the heater plate 5020.FIG. 20 illustrates this effect by indicating the distributed forces orpressures that are applied to the lid 5114, variable portion 5116 andthe base 5112 by the arrows shown.

The force required for compression of the variable portion 5116 when thewater reservoir 5110 is connected with the humidifier 5000 is primarilyin the direction tangential to the pivoted opening direction of thewater reservoir 5110, which may be the same direction as the normal to asurface of the conductive portion, and is reacted by the water reservoirdock 5130 at its contacting points and/or surfaces, thereby pushing thebase 5112 of the water reservoir 5110 and the heater plate 5120together. As a corollary, a decrease of the compression resulting in anincrease in height of the variable portion 5116 will reduce the forcebetween the base 5112 and the heater plate 5120. In other words, varyingthe height of the variable portion in the reservoir varies a level ofthermal engagement between the conductive portion and the heater plate.

The water reservoir 5110 may be configured so that the direction ofthermal engagement with the heater plate 5120 is in the same directionas the normal direction of a surface of the conductive portion.

The magnitude of this force may be between about 5 N and about 15 N whenmeasured at the heater plate 5120 when the water reservoir 5110 isplaced in the water reservoir dock 5130. However, it should beunderstood that different configurations of the water reservoir 5110 mayrequire different magnitudes of compression force. The magnitude of thisforce may be altered by modifying the design of any or all of the seal5116, the lid 5114, the base 5112, or the reservoir dock 5130. Forinstance if the variable portion 5116 was constructed of a material withhigher Young's modulus, it would correspondingly increase the magnitudeof the force. It should be noted that FIG. 20 only shows forces andpressures in the vertical direction.

Furthermore, when the water reservoir 5110 is connected with thehumidifier 5000, the pressurized flow of breathable air received fromthe PAP device pressurizes the interior of the reservoir 5110 and mayfurther encourage an expansion of the variable portion 5116 that pushesthe base 5112 of the water reservoir 5110 against the heater plate 5120to improve the level of thermal engagement, or the level of thermalcontact, between the heater plate 5120 and the base 5112. FIG. 21illustrates this effect by indicating the distributed forces orpressures that are applied to the lid 5114 and the base 5112 by thearrows shown. The presence of above-atmospheric pressure within thewater reservoir 5110 is shown to result in forces in the direction ofthermal engagement, and is reacted by the water reservoir dock 5130 atits contacting surfaces, thereby pushing the base 5112 of the waterreservoir 5110 and the heater plate 5120 towards each other in thedirection of thermal engagement. The magnitude of this force may bebetween about 5 N and about 15 N when measured at the heater plate 5120at 20 cm H₂O of pressure. However, it should be understood thatdifferent configurations of the water reservoir 5110 may requiredifferent magnitudes of force, which may be achieved by varying thesurface area that the pressure acts on, or the effective pressure thatacts on the surface. Such changes may be achieved, for example, by apressure regulating valve. It should be noted that FIG. 21 only showsforces and pressures in the vertical direction, as the thermalengagement occurs in the vertical direction. Thus, the variable portionin the reservoir 5110 enables movement of the reservoir base 5112 and/orthe reservoir lid 5114 in response to an increase in pressure aboveatmospheric pressure in the reservoir 5110 to improve thermal engagementof the reservoir base 5112 with the heater plate 5020. It is envisagedthat, in another arrangement, substantially the same effects as thosedescribed above may be achieved with a non-opening variable portion of awater reservoir 5110. The water reservoir 5110 and the reservoir dock5130 may be substantially arranged so that elasticity or flexibility isprovided by an elastomeric material or a joint that allows freedom ofmovement (e.g. a sliding connection, or a concertina section of pliableplastic or a flexible portion in the water reservoir) in the directionof the heat transfer. In this configuration the lid 5114 and the base5112 may be unconstrained relative to each other in the direction ofthermal contact The reservoir 5110 may then be constrained in thedirection of the heat transfer in another manner (e.g. by a waterreservoir dock or a similar housing) to create a force that reacts tobalance the pressure created in the interior of the reservoir 5110 bythe pressurized flow of breathable air, wherein some of the reactionforce may occur at the heater plate 5120 to improve thermal contact. Insuch arrangements, another opening to re-fill the water reservoir 5110may be introduced on the reservoir 5110, such as on the lid 5114, and itmay comprise a separate seal. Such an opening may be configurablebetween an open and a closed position, for example, by a cap or arefilling lid. FIG. 34 shows an example of such an arrangement,including a base 5174, a top 5176, a variable portion 5178 and are-filling cap 5180. The base, the top and the variable portion may beaffixed together in this arrangement, and in such a case re-filling ofthe reservoir would be accommodated by the re-filling cap, 5180. There-filling cap 5180 may be placed such that when the humidifierreservoir 5110 is engaged with the reservoir dock 5130 the re-fillingcap 5180 is not accessible. Such an arrangement may preserve theadvantage described above, namely that the reservoir 5110 is not able tobe re-filled while it is engaged with the reservoir dock 5130.Furthermore, the variable portion 5178 may be replaced by any mechanismknown in the art that is able to accommodate a change in vertical lengthwithin a reservoir.

In a yet another alternate arrangement, the pressurized flow ofbreathable air may be used to improve the level of thermal contactbetween the humidifier reservoir 5110 and the heater plate 5120 bypressurisation or inflation of a chamber, body or surface that acts onthe humidifier reservoir 5110, which in turn may push the waterreservoir 5110 and the heater plate 5120 together in the direction ofthermal engagement. Similarly the supply of the pressurized flow ofbreathable air may pressurize or inflate a chamber, body or surface thatacts upon the heater plate to push the heater plate 5120 and waterreservoir 5110 together in the direction of thermal engagement.

The chamber may be arranged on the outside of the reservoir andcommunicated with the flow of breathable gas. A surface of the chambermay be connected with the reservoir in the direction of thermalengagement so that varying the pressure of the flow of breathable gas inthe reservoir varies the size of the chamber and changes a level ofthermal engagement between the conductive portion and the heater plate.The chamber being arranged to push the reservoir towards the heaterplate 5020 and/or the heater plate 5020 towards the reservoir when thesize of the chamber increases.

In an alternate arrangement of the reservoir dock 5160, wherein theopening is substantially in the horizontal plane and thus the waterreservoir 5110 is inserted from above or below the reservoir dock 5160as described above, the water reservoir dock 5160 may include aretaining mechanism (for example, a lid that closes above the waterreservoir 5110) to hold the water reservoir 5110 in its intendedposition. In such an arrangement, the reservoir dock lid may beconfigured to compress the variable portion 5116 which would in turnpush the reservoir 5110 against the heater plate 5120. Similarly, thereservoir 5110 may be configured so that when the reservoir dock lid isclosed, and the pressurized flow of breathable air pressurizes theinterior of the reservoir 5110, it pushes the reservoir lid 5114 and thereservoir base 5112 apart that acts on the variable portion to try toexpand or un-compress the variable portion, and in turn enhances thelevel of thermal contact between the reservoir base 5112 and the heaterplate 5120.

The level of thermal contact may also be improved using a spring loadedor sprung heater plate as is known in the prior art. The heater platemay be constructed with a convex or domed shape towards the humidifierreservoir 5110 so that when the humidifier 5110 is engaged with thereservoir dock 5130 the convex heater plate is flattened, whichgenerates a clamping force pushing the heater plate 5120 to the waterreservoir 5110. Similarly, the conductor plate 5152 of the waterreservoir 5110 may be domed or convex shaped and be configured to beflattened towards to the heater plate when the water reservoir 5110 isengaged in the dock cavity 5180 of the humidifier 5000.

Any one of the above means of improving thermal contact may be usedindependently of each other, or in any combination thereof, including incombination with any prior art means of achieving or improving thermalengagement between the humidifier reservoir and the heater plate.

Reservoir Inlet/Outlet

In one arrangement, the reservoir inlet 5118 and the reservoir outlet5122 may be oriented horizontally and on the same surface, as shown inFIG. 12. The reservoir inlet 5118 includes an inlet tube 5124 thatextends from the exterior of the reservoir into the interior volume ofthe reservoir to provide a flow path for the inlet flow of pressurizedgas into the reservoir 5110. The reservoir outlet 5122 includes anoutlet tube 5126 that extends from the interior of the reservoir 5110 tothe exterior of reservoir 5110 to provide a flow path for the outletflow of humidified pressurized gas from the reservoir 5110, as shown inFIG. 22.

As shown in FIG. 22-23, the reservoir 5110 may include an end wall 5128that is near and opposed to an interior end 5125 of the inlet tube 5124.The inlet tube 5124 directs the inlet airflow to the inner end wall 5128of the reservoir 5110 thus directing the air to flow across the wholewater surface before it reaches an interior end 5127 of the outlet tube5126 and flows out of the outlet 5122 through the outlet tube 5126. FIG.24-27 show examples of other arrangements, wherein the reservoir 5110may include a turning vane 5136 which is placed near the interior end5125 of the inlet tube 5124. The turning vane 5136 may be formed as anextension of the inlet tube 5124 as shown in FIG. 26-27, or the turningvane 5136 may be a separate component located adjacent to or coupledwith the inlet tube 5124. The turning vane may also be profiled as shownin FIG. 26-27.

The water reservoir 5110 is preferably configured to provide tiltspillback protection from the water flowing back through the outlet tube5126 or the inlet tube 5124. Water egress through the inlet tube 5124 isparticularly undesirable as it may introduce water into the PAP device4000 and may damage electronic components (such as an electric motor, aflow sensor or a printed circuit board) from exposure to water. In onearrangement the reservoir 5110 achieves spillback protection byarranging the inlet tube outlet 5125 so that when the reservoir 5110 isrotated by 90 degrees in any direction from its working, horizontalorientation the given maximum volume of water is able to be stored inthe reservoir 5110 without reaching the inlet tube outlet 5125.

In another arrangement, the reservoir 5110, the axes of inlet tube 5124and the outlet tube 5126 may intersect when viewed from above as shownin FIG. 28-29. The inlet tube 5124 and outlet tube 5126 are notconnected to each other as one of the tubes passes below the other tube,such as the inlet tube 5124 passes below the outlet tube 5126.

This configuration may improve the tilt spillback protection byarranging the inlet tube 5124 and the outlet tube 5126 such that whenthe reservoir 5110 is tilted to its side (substantially about the axisof the inlet/outlet), and water reaches the lower of the interior end5125 of the inlet tube 5124 or the interior end 5127 of the outlet tube5126, the water must rise higher to exit the reservoir 5110 as shown inFIG. 29. In comparison, if the inlet tube 5124 and the outlet tube 5126were parallel, when water reaches the lower of the interior end 5125 ofthe inlet 5124 or the interior end 5127 of the outlet tube 5126 it wouldthen be able to freely flow out of the reservoir 5110 through the inlettube 5124 or the outlet tube 5126.

One example of the above spillback prevention technology arranges theinlet tube 5124 and the outlet tube 5126 such that the axes defined bythe interior end 5125 of the inlet 5124 and the exterior end 5190 of theoutlet 5126 and the interior end 5127 of the outlet 5126 and theexterior end 5188 of the inlet 5124 are substantially parallel to eachother.

Crossing the inlet tube 5124 and the outlet tube 5126 creates ageometric configuration wherein the water level must reach the higher ofthe inlet and outlet tube interior ends 5125, 5127 to be able to exitthe reservoir 5110, or the water level must reach the lower of the inletand outlet tube interior ends 5125, 5127 and extend along the entirelength of the inlet tube 5124 or outlet tube 5126 to be able to exit thereservoir 5110.

Simplified representations of the effects created by crossed inlet andoutlet tubing are shown in FIG. 35-38 (FIG. 35-36 shows oneconfiguration, FIG. 37-38 another), wherein the internal surfaces areshown by dotted lines. These figures show alternate arrangements of awater reservoir 5110, with an inlet 5118 and an outlet 5122 thatrespectively include an inlet tube 5124 and an outlet tube 5126extending into a cavity or interior volume of the reservoir, andterminating at an interior end 5125 of the inlet tube 5124 and aninterior end 5127 of the outlet tube 5126 respectively. FIG. 35-36 showa configuration wherein the axes of the tubing substantially intersectwhen viewed from the side (as shown in FIG. 36), and FIG. 37-38 show analternate configuration wherein the axes of the tubing are substantiallyparallel when viewed from the side (as shown in FIG. 38). In FIG. 35-38,a volume of water 5182 is assumed to fill approximately half of thevolume of the reservoir 5110, and is indicated by the dotted linesextending horizontally approximately at the mid-height of the reservoir5110.

When the water reservoir 5110 is oriented as shown in FIG. 35-36, thearrangement of the inlet tube 5124 and the outlet tube 5126 requires thewater level 5184 to rise above the entire length of the inlet tube 5124to reach the exterior end of the inlet tube or to rise above theinterior end 5127 of the outlet tube 5126 if any water 5182 is to exitthe water reservoir 5110. On the other hand, in the arrangement shown inFIG. 36-37 the water level 5184 only needs to rise as high as the lowerof the inlet tube 5124 or the outlet tube 5126 in order to exit thewater reservoir 5110. As the water level 5184 will change as a functionof the orientation of the water reservoir 5110, this effect of crossingthe inlet tube 5124 and the outlet tube 5126 may be re-created at anyorientation as required by re-orienting the inlet tube 5124 and theoutlet tube 5126 to suit the shape of the water reservoir 5110.

The inlet tube may deliver a supply of breathable gas into the cavity ofthe reservoir and the outlet tube may deliver a humidified supply ofbreathable gas from the cavity. The inlet interior end and the outletinterior end are located within the cavity and the inlet exterior endand the outlet exterior end are located in one of the plurality of wallsof the cavity. A first axis is defined by the inlet interior end and theinlet exterior end and a second axis is defined by the outlet interiorend and the outlet exterior end When the reservoir is tiltedapproximately 90° to normal working orientation the first axis is on afirst angle such that the inlet interior end and the inlet exterior endare positioned at different heights, such that the predetermined maximumvolume of water is below at least one of the inlet interior end or theinlet exterior end to prevent spillback of water through the inlet tube.Furthermore, when the reservoir is tilted approximately 90° to normalworking orientation the second axis is on a second angle such that theoutlet interior end and the outlet exterior end are positioned atdifferent heights, such that the predetermined maximum volume of wateris below at least one of the outlet interior end or the outlet exteriorend to prevent spillback of water through the outlet tube.

Overfill Prevention

Another aspect of this technology is the inclusion of an overfillprotection element configured to prevent filling the reservoir above themaximum volume of water when filling the humidifier reservoir in itsopen configuration. In onearrangement as seen in FIGS. 30a and 30b , thehumidifier reservoir includes a pair of rails 5112.3 (one on each side),a flange 5112.1 and a lip 5112.2 extending from the flange 5112.1, andthe overfill protection element may include at least one orifice 5138 inthe water reservoir 5110 to indicate over-filling. According to thisaspect of the technology, when the water reservoir 5110 is beingre-filled with the reservoir lid 5114 open, over-filling beyond apredetermined level or the maximum capacity or volume for the reservoir5110 would cause water to spill out from the orifice 5138. The waterspilling out through orifice 5138 indicating that a maximum capacity hasbeen reached and preventing the water reservoir 5110 from being filledbeyond a predetermined level or maximum capacity. Advantageously waterwould spill out only through the at least one orifice 5138 rather thanfrom all areas of the water reservoir resulting in less overflowspillage for the user to clean up. Thus, the at least one orificedefines an egress path of water when the predetermined maximum volume ofwater is exceeded. FIG. 30a show the water reservoir 5110 in its openconfiguration, wherein an upper flange of the base 5112 does not spanthe perimeter of the entire opening, creating an orifice 5138. FIG. 30bshows a zoomed in section of the base 5112 indicating the at least oneorifice 5138. The at least one orifice 5138 may be in the form of one ormore apertures, holes, slits or slots, or any other form that allowscommunication of fluid into and out of the water reservoir 5110. The atleast one orifice 5138 may be formed in one or more positions around theupper flange of the base 5112.

In an alternate arrangement, the overfill protection element may includea sloped profile 5139. As shown in FIGS. 30c and 30d , the reservoirbase 5112 may be arranged so that its side profile has a sloped profile5139 in one or more directions. This arrangement may also indicateover-filling when the reservoir base 5112 is re-filled with liquid orwater. In this arrangement, when the reservoir lid 5114 is in its openconfiguration, water may spill out at the base of the sloped profile5139 rather than from all areas of the reservoir. Thus, the slopedprofile defines an egress path of water when the predetermined maximumvolume of water is exceeded. Advantages of the above methods may be thatover-filling may become more difficult than has been in the prior art,and presents another advantage that in response to attemptedover-filling, spillage may occur at more predictable locations.

Another aspect of this technology is that when the water reservoir 5110is in its closed position, a seal 5192 sealingly engages the base 5112and the reservoir lid 5114 and blocks or seals the orifice 5138 orsloped profile 5139 preventing fluid communication into and out of thewater reservoir 5110. One arrangement of this feature is shown in FIG.31, which shows that when the reservoir lid 5114 is closed (lid notshown in this image), the seal 5192 sealingly engages with the base 5112on the outside of the orifice 5138 and no longer allows communication ofliquid or air into and out of the water reservoir 5110 through theorifice 5138. Similarly the seal 5192 would engage with the base 5112 tosurround the edges of the sloped profile preventing communication ofliquid or air into and out of the water reservoir 5110 through thesloped profile 5139. In some arrangements the seal 5192 may beintegrated with the variable portion 5116 as described above.Alternatively the seal 5192 may be a separate seal that may be used in areservoir with or without a variable portion.

Retaining Clip

The reservoir lid 5114 may include a means by which the water reservoir5110 is to be retained in the water reservoir dock 5130 once the twomembers are engaged with each other. In one arrangement a retainingmeans may be a protrusion, or a clip, 5142 on the reservoir lid 5114 asshown in FIGS. 32-33. FIGS. 32-33 show a water reservoir 5110 and thereservoir dock 5130. Here, a protrusion, or a clip, 5142 on thereservoir lid 5114 removably engages with a corresponding dock lockingrecess 5144 in the water reservoir dock 5130 when the water reservoir5110 is inserted into the water reservoir dock 5130. This connectionsecures the water reservoir 5110 relative to the water reservoir dock5130. As described above the variable portion 5116 of the reservoir iscompressed to enable insertion of the reservoir into the dock 5130. Thecompression of the variable portion 5116 allows a portion of thereservoir 5110 to slide into the dock 5130 and allows the protrusion orclip 5142 to slide initially under the outer edge surface of the dock5130 to reach the dock locking recess 5144. The compression forceapplied to the reservoir for insertion may then be released to allow theprotrusion or clip 5142 to engage with the dock locking recess 5144 andsecuring of the reservoir 5110 within the dock 5130. When the reservoir5110 is secured within the dock 5130 the variable portion 5116 is nolonger in or in a reduced compressed state. Similarly, in order to beable to remove the water reservoir 5110 from the water reservoir dock5130, the variable portion 5116 must be compressed as to disengage thelid protrusion 5142 from the dock locking recess 5144. It would be clearto those skilled in the art that in an alternativer arrangement the lidprotrusion 5142 may be a recess, and the dock locking recess 5144 may bea corresponding protrusion. Alternatively one of any number of retainingmeans that are known in the art may be used to achieve the same means.

5.5.2.3 Heater Plate 5120

A heater plate 5120 is used to transfer heat to the water reservoir5110. The heater plate 5120 may form a part of the reservoir dock 5130,and may be located on or near the base of the humidifier 5000 as shownin FIG. 14. The heater plate 5120 may be formed, for example, of anickel chrome alloy or anodised aluminium.

5.6 Glossary

In certain forms of the present technology, one or more of the followingdefinitions may apply. In other forms of the present technology,alternative definitions may apply.

5.6.1 General

Air: Air will be taken to include breathable gases, for example air withsupplemental oxygen.

Continuous Positive Airway Pressure (CPAP): CPAP treatment will be takento mean the application of a supply of air or breathable gas to theentrance to the airways at a pressure that is continuously positive withrespect to atmosphere, and preferably approximately constant through arespiratory cycle of a patient. In some forms, the pressure at theentrance to the airways will vary by a few centimeters of water within asingle respiratory cycle, for example being higher during inhalation andlower during exhalation. In some forms, the pressure at the entrance tothe airways will be slightly higher during exhalation, and slightlylower during inhalation. In some forms, the pressure will vary betweendifferent respiratory cycles of the patient, for example being increasedin response to detection of indications of partial upper airwayobstruction, and decreased in the absence of indications of partialupper airway obstruction.

5.6.2 Humidification System

Water reservoir: A water reservoir, or water tub, or humidifierreservoir, is a chamber that forms a part of the humidification system.It is configured to contain a body of liquid (e.g., water) aimed atimparting additional humidity to the flow of breathable air that passesthrough the water reservoir. It may comprise an air inlet and an airoutlet, as well as a means (such as an opening or an openable lid) offilling the water reservoir with water.

5.6.3 Anatomy of the Respiratory System

Diaphragm: A sheet of muscle that extends across the bottom of the ribcage. The diaphragm separates the thoracic cavity, containing the heart,lungs and ribs, from the abdominal cavity. As the diaphragm contractsthe volume of the thoracic cavity increases and air is drawn into thelungs.

Larynx: The larynx, or voice box houses the vocal folds and connects theinferior part of the pharynx (hypopharynx) with the trachea.

Lungs: The organs of respiration in humans. The conducting zone of thelungs contains the trachea, the bronchi, the bronchioles, and theterminal bronchioles. The respiratory zone contains the respiratorybronchioles, the alveolar ducts, and the alveoli.

Nasal cavity: The nasal cavity (or nasal fossa) is a large air filledspace above and behind the nose in the middle of the face. The nasalcavity is divided in two by a vertical fin called the nasal septum. Onthe sides of the nasal cavity are three horizontal outgrowths callednasal conchae (singular “concha”) or turbinates. To the front of thenasal cavity is the nose, while the back blends, via the choanae, intothe nasopharynx.

Pharynx: The part of the throat situated immediately inferior to (below)the nasal cavity, and superior to the oesophagus and larynx. The pharynxis conventionally divided into three sections: the nasopharynx(epipharynx) (the nasal part of the pharynx), the oropharynx(mesopharynx) (the oral part of the pharynx), and the laryngopharynx(hypopharynx).

5.6.4 Materials

Silicone or Silicone Elastomer: A synthetic rubber. In thisspecification, a reference to silicone is a reference to liquid siliconerubber (LSR) or a compression moulded silicone rubber (CMSR). One formof commercially available LSR is SILASTIC (included in the range ofproducts sold under this trademark), manufactured by Dow Corning.Another manufacturer of LSR is Wacker. Unless otherwise specified to thecontrary, a preferred form of LSR has a Shore A (or Type A) indentationhardness in the range of about 35 to about 45 as measured using ASTMD2240.

Polycarbonate: a typically transparent thermoplastic polymer ofBisphenol-A Carbonate.

5.7 Other Remarks

*A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in the Patent and TrademarkOffice patent file or records, but otherwise reserves all copyrightrights whatsoever.

Unless the context clearly dictates otherwise and where a range ofvalues is provided, it is understood that each intervening value, to thetenth of the unit of the lower limit, between the upper and lower limitof that range, and any other stated or intervening value in that statedrange is encompassed within the technology. The upper and lower limitsof these intervening ranges, which may be independently included in theintervening ranges, are also encompassed within the technology, subjectto any specifically excluded limit in the stated range. Where the statedrange includes one or both of the limits, ranges excluding either orboth of those included limits are also included in the technology.

Furthermore, where a value or values are stated herein as beingimplemented as part of the technology, it is understood that such valuesmay be approximated, unless otherwise stated, and such values may beutilized to any suitable significant digit to the extent that apractical technical implementation may permit or require it.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this technology belongs. Although any methods andmaterials similar or equivalent to those described herein can also beused in the practice or testing of the present technology, a limitednumber of the exemplary methods and materials are described herein.

When a particular material is identified as being preferably used toconstruct a component, obvious alternative materials with similarproperties may be used as a substitute.

It must be noted that as used herein and in the appended claims, thesingular forms “a”, “an”, and “the” include their plural equivalents,unless the context clearly dictates otherwise.

All publications mentioned herein are incorporated by reference todisclose and describe the methods and/or materials which are the subjectof those publications. The publications discussed herein are providedsolely for their disclosure prior to the filing date of the presentapplication. Nothing herein is to be construed as an admission that thepresent technology is not entitled to antedate such publication byvirtue of prior invention. Further, the dates of publication providedmay be different from the actual publication dates, which may need to beindependently confirmed.

Moreover, in interpreting the disclosure, all terms should beinterpreted in the broadest reasonable manner consistent with thecontext. In particular, the terms “comprises” and “comprising” should beinterpreted as referring to elements, components, or steps in anon-exclusive manner, indicating that the referenced elements,components, or steps may be present, or utilized, or combined with otherelements, components, or steps that are not expressly referenced.

The subject headings used in the detailed description are included onlyfor the ease of reference of the reader and should not be used to limitthe subject matter found throughout the disclosure or the claims. Thesubject headings should not be used in construing the scope of theclaims or the claim limitations.

Although the technology herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thetechnology. In some instances, the terminology and symbols may implyspecific details that are not required to practice the technology. Forexample, although the terms “first” and “second” may be used, unlessotherwise specified, they are not intended to indicate any order but maybe utilised to distinguish between distinct elements. Furthermore,although process steps in the methodologies may be described orillustrated in an order, such an ordering is not required. Those skilledin the art will recognize that such ordering may be modified and/oraspects thereof may be conducted concurrently or even synchronously.

It is therefore to be understood that numerous modifications may be madeto the illustrative embodiments and that other arrangements may bedevised without departing from the spirit and scope of the technology.

6 REFERENCE SIGNS LIST 7 CITATIONS 7.1 Patent Literature 7.2 Non-PatentLiterature

The invention claimed is:
 1. A water reservoir for use with arespiratory pressure therapy (RPT) device for pressurising breathableair to treat a respiratory disorder in a patient, the water reservoircomprising: a water reservoir base configured to hold a volume of waterto be used for humidification of the breathable air, the water reservoirbase having a reservoir base handling portion, the water reservoir basehaving horizontal rail portions configured to horizontally sliderelative to a water reservoir dock associated with the RPT device; and awater reservoir lid connected to the water reservoir base, the waterreservoir lid including an upper surface with a clip configured toengage with a recess of the water reservoir dock, thus securing thewater reservoir to the water reservoir dock, the water reservoir lidincluding a deflectable spring and a reservoir lid handling portion, thewater reservoir lid having an inlet and an outlet both disposed on aleading end of the water reservoir that is configured to be insertedinto the water reservoir dock by horizontal sliding on the horizontalrail portions, the reservoir base handling portion and the reservoir lidhandling portion being located on a trailing end of the water reservoir,the leading end with the inlet and the outlet being positioned on afirst side of the water reservoir and the trailing end with thereservoir base handling portion and the reservoir lid handling portionbeing positioned on a second side of the water reservoir, opposite thefirst side, wherein the reservoir lid handling portion and the reservoirbase handling portion are configured to be simultaneously graspable by ahand of the patient to move at least one portion of the water reservoirlid including the clip, relative to the water reservoir base and againstthe bias of the spring to cause disengagement of the clip from therecess, thus allowing removal of the water reservoir from the waterreservoir dock by horizontally pulling the reservoir base handlingportion and the reservoir lid handling portion to slide the waterreservoir via the pair of horizontal rail portions out of engagementwith the water reservoir dock, wherein the spring does not seal betweenthe water reservoir base and the water reservoir lid.
 2. The waterreservoir of claim 1, wherein the spring is in the form of acantilevered member with a proximate end and a free end, the springbeing deflected when a force is applied and returning to a lessdeflected state when the force is released.
 3. The water reservoir ofclaim 1, wherein the water reservoir lid is configured to receive adownward force to deflect the spring to allow a portion of the waterreservoir lid with the clip to be moved when removing the waterreservoir from the water reservoir dock, and wherein the reservoir lidhandling portion and the reservoir base handling portion are configuredto allow the patient to apply a horizontal pulling force whilst thedownward force is applied in order to remove the water reservoir fromthe water reservoir dock, the horizontal pulling force beingperpendicular to the downward force.
 4. The water reservoir of claim 1,wherein the water reservoir lid comprises two parts that are assembledwith the spring therebetween.
 5. The water reservoir of claim 1, whereinthe spring is positioned within the water reservoir lid, and not betweenthe water reservoir base and the water reservoir lid.
 6. The waterreservoir of claim 1, wherein the water reservoir must be removed fromthe water reservoir dock to allow refilling with water.
 7. The waterreservoir of claim 1, wherein the reservoir lid handling portion and/orthe reservoir base handling portion includes a grip portion.
 8. Thewater reservoir of claim 7, further comprising a latch to secure thewater reservoir lid and the water reservoir base, the latch beingpositioned on the trailing end between the reservoir lid handlingportion and the reservoir base handling portion, the reservoir lidhandling portion having an upper surface configured to receive adownward gripping force vertically aligned with the latch, and thereservoir base handling portion has a lower surface to receive an upwardgripping force opposed to the downward gripping force and verticallyaligned with the latch.
 9. The water reservoir of claim 1, wherein thewater reservoir lid and the water reservoir base are connected via apair of joints positioned proximate the leading end of the waterreservoir, the pair of joints defining a pivot axis about which thewater reservoir lid is pivotable relative to the water reservoir base,the reservoir lid handling portion and the reservoir base handlingportion being positioned on the water reservoir at the trailing end thatis opposite to the leading end, the pair of j oints allowing the waterreservoir lid to swing open from the trailing end, the horizontal railportions being oriented in a horizontal sliding direction that isperpendicular to the pivot axis.
 10. The water reservoir of claim 1,further comprising an elastomeric seal between the water reservoir lidand the water reservoir base.
 11. The water reservoir of claim 10,further comprising a flange extending inwardly and forming an opening ofthe water reservoir base, wherein the flange further comprises an innerlip positioned radially inward of the seal to discourage egress ofliquid from the water reservoir.
 12. The water reservoir of claim 1,wherein the water reservoir is configured so that, when the waterreservoir is at least partly received in the water reservoir dock, thespring urges the water reservoir lid to effect and maintain engagementbetween the clip and the recess and secure the water reservoir in thewater reservoir dock.
 13. The water reservoir of claim 1, wherein thewater reservoir base includes a conductor plate constructed from a heatconducting material such that when the water reservoir is at leastpartly received in the water reservoir dock, the conductor platethermally engages with a spring-loaded heater plate on the waterreservoir dock so as to allow transfer of heat from the heater plate tothe conductor plate during operation of the heater plate.
 14. The waterreservoir of claim 1, wherein to remove the water reservoir from thewater reservoir dock, (a) the reservoir base handling portion and thereservoir lid handling portion are squeezed together to disengage theclip from the recess, and (b) whilst squeezing the reservoir basehandling portion and the reservoir lid handling portion, the waterreservoir is pulled to slide along the horizontal rail portions in ahorizontal direction to remove the water reservoir from the waterreservoir dock.
 15. The water reservoir of claim 1, wherein a heightand/or shape of the water reservoir are dimensioned such that to engagethe water reservoir with the water reservoir dock, the spring isdeflected.
 16. The water reservoir of claim 1, wherein during insertionof the water reservoir at least partly into the water reservoir dock,deflection of the spring allows the clip to initially slide relative toa surface of the water reservoir dock before deflecting into the recess,at which point the spring at least partially springs back, thus securingthe water reservoir within the water reservoir dock.
 17. The waterreservoir of claim 1, wherein the clip is tapered so as to increase inheight in a direction opposite to a direction of insertion of the waterreservoir into the water reservoir dock.
 18. The water reservoir ofclaim 1, wherein the inlet and the outlet are positioned at differentheights on a vertical side wall of the water reservoir lid, the inletand the outlet having respective openings defined in a common verticalplane, and wherein the water reservoir is configured to horizontallyslide on the horizontal rail portions at least partly into the waterreservoir dock such that the inlet and outlet, respectively, sealinglyengage a dock inlet and a dock outlet of the water reservoir dock, andsuch that locking the clip within the recess secures the water reservoirand maintains the water reservoir inlet and outlet sealed to therespective dock inlet and dock outlet.
 19. An RPT device including: ablower to generate a flow of the pressurized breathable air; the waterreservoir dock including a heater plate; and the water reservoir ofclaim 1, wherein the water reservoir includes a conductor plate thatengages with the heater plate, and the horizontal rail portions areconfigured to slide in a horizontal direction to engage within the waterreservoir dock, wherein the water reservoir is movable along thehorizontal rail portions between a connected position and a removedposition, the water reservoir being operatively connected to the waterreservoir dock in the connected position in which the clip is securedwith the recess of the water reservoir dock, and the water reservoirbeing separated from the water reservoir dock in the removed position,wherein the reservoir base handling portion includes a downwardly facingbottom surface, wherein, when the water reservoir is in the connectedposition, 1) the reservoir lid handling portion and the downwardlyfacing bottom surface of the reservoir base handling portion remain inan exposed position for access by the hand of the patient, and 2) theconductor plate of the water reservoir is spaced horizontally inboardfrom the downwardly facing bottom surface bottom surface of thereservoir base handling portion in a shielded position so as to beprotected from access by the patient's hand when the patient grasps thereservoir base handling portion and the reservoir lid handling portionin the exposed position, and wherein to move the water reservoir fromthe connected position to the removed position, at least one portion ofthe water reservoir lid is pressed towards and relative to the waterreservoir base, against the bias of the spring, to disengage the clipfrom the recess, and the water reservoir is removable from the waterreservoir dock by sliding on the horizontal rail portions.
 20. A waterreservoir for use with a respiratory pressure therapy (RPT) device forpressurising breathable air to treat a respiratory disorder in apatient, the water reservoir comprising: a water reservoir baseconfigured to hold a volume of water to be used for humidification ofthe breathable air; a water reservoir lid connected to the waterreservoir base, the water reservoir lid including a clip configured toengage with a recess of a water reservoir dock associated with the RPTdevice, thus securing the water reservoir to the water reservoir dock,the water reservoir lid including a spring; and a reservoir handle withupper and lower handling portions graspable by the patient to movablycompress at least a portion of the water reservoir lid against the biasof the spring to disengage the clip from the recess, thus allowingremoval of the water reservoir from the water reservoir dock, whereinthe spring is in the form of a cantilevered member with a proximate endand a free end, the spring being deflected when a force is applied andreturning to a less deflected state when the force is released, whereinthe spring does not seal between the water reservoir base and the waterreservoir lid, wherein the spring is positioned within the waterreservoir lid, and not between the water reservoir base and the waterreservoir lid, wherein the water reservoir must be removed from thewater reservoir dock to allow refilling with water, wherein the upperhandling portion is formed on the water reservoir lid and the lowerhandling portion is recessed into the water reservoir base, wherein atleast one of the upper handling portion and the lower handling portionincludes a grip, further comprising a latch to secure the waterreservoir lid and the water reservoir base, the latch being positionedbetween the upper and lower handling portions, wherein the waterreservoir lid and the water reservoir base are connected via a pair ofjoints positioned proximate an insertion end of the water reservoir, theupper and lower handling portions being positioned on the waterreservoir at a graspable end that is opposite to the insertion end, thepair of joints allowing the water reservoir lid to swing open from thegraspable end, further comprising an elastomeric seal between the waterreservoir lid and the water reservoir base, and further comprising aninner lip positioned radially inward of the seal when the waterreservoir lid is in a closed position to discourage egress of liquidfrom the water reservoir.